Anyone Got the 7D?

[DavidEccleston]

Think of pixel wells as little dividers, putting more or less dividers won't increase noise.

From how I read the noise myth post, you will see increased noise, on a 100% crop, and not on a resize. I shall demonstrate my interpretation of that thread will little number buckets.


Lets say we have two sensors, the first 2x2 pixels, and the second 4 times the resolution, 4x4 pixels, in the same physical space. We've somehow convinced the photons to behave identically twice. The photons land such that each of the larger pixels, on the low res sensor, receive 8 units of light.


8 8
8 8


However, the light isn't really evenly distrubuted, and the smaller pixels, on the higher res sensor, show that. I've added some spacing to emphasis the where the original pixels were. Assume they're all nice and evenly spaced physically.


3 2 2 1
1 2 1 4

2 3 3 1
3 0 1 3


Each 2x2 block adds up to the same 8 photons that hit the same sensor area. While the total photon count is identical, to account for the lesser number of photons going to hit each pixel of the sensor, we need these values multiplied by 4 before being store in the JPEG.





12 08 08 04
04 08 04 16

08 12 12 04
12 00 04 12
<div>With such a small number of photons (low light, high ISO), the noise is quite apparent. A resize of the 4x4 image into a 2x2 image would smooth back to 8, effectively blending out the noise. The myth busting is essentially if you're against the 7D because 18MP will be noisier than the 10MP on your 40D, you're silly. You can resize to 10MP and it will look the same. In good light you won't see the noise, and you can take advantage of the extra resolution and crop, if you'd like.</div>



I could be wrong in how I'm interpreting the noise myth post. My interpretation still shows the noise being a mythical reason to avoid higher density sensors. It works out mathematically. It also shows that 100% there will be extra noise.

[Daniel Browning]

Good explanation, David. I would add that there are parts of this that are objective, and parts that are subjective. Your post was about the objective parts:

• 18mp will have more noise per pixel than 10mp
• 18mp downsized to 10mp will have the same noise per pixel as 10mp.

The subjective parts are about what the impact of "more noise per pixel" is:

• For some people (e.g. me), having more noise per pixel still looks like the "same" noise, because the noise is at a level of detail smaller than the 10mp camera. This is subjective, though, because some people see the higher noise per pixel as worse than 10mp, even though it is at a much smaller level.
• Downsampling from 18mp to 10mp is one way to deal with the noise, but it's far better to use software noise reduction, which can use the higher resolution to great advantage. But NR is a whole realm of subjectivity.

So it's possible that Fast Glass is just talking about one of the subjective things. For example, I think it's OK to say that 18mp does not have "more" noise than 10mp, even though it does have more noise per pixel, because the way I see it, the "noise per detail" is still the same (even *without* downsampling or NR). But I recognize that it's only my personal impression from viewing images, and others see it differently.


FWIW.

[Jon Ruyle]

The myth busting is essentially if you're against the 7D because 18MP will be noisier than the 10MP on your 40D, you're silly.

That's it in a nutshell. You've condensed a 50+ post thread into one line

[Oren]

Don, is the 7D viewfinder bigger (physically)? Of course it's a bit bigger since it's 100% coverage and 1x magnification, but is it much much bigger? It doesn't make sense to me since the sensor is still an APS-C sensor. Anyhow, I'd love to have a 7D of course, what I was saying is that it's not *that* appealing to me and doesn't worth the extra $700 - I'd put that toward a new lens and other gear.

[alex]

I just wanna jump in here and say that, while I am waiting for Bryan's review on this beasty, my initial thoughts and feelings are that if I had the money to burn, I would sell my XSi and get the 7D sooner than I could even finish typing this sente....


Do I have it in my hands yet? Alas, no. It was a dream.

[Don Burkett]

I have put up some images of the 7D. Various ISO's, Crops, Lighting Challenges, etc.


I'm not trying to demonstrate any point, just sharing if you want to view them. [View:http://www.pbase.com/dbrasco/canon_7d]

[EdN]

Don


The images are great and the image quality looks really good too. How do you like the AF system? Have you had a chance to see how it tracks moving objects yet?

[Don Burkett]

Thanks, for the comments. The autofocus is superior to what I'm used to with the 40d. At the same time, I don't use autofocus all that often though I had no trouble tracking some sea gulls the other day. I am really pleased with the exposure handling.

[Fast Glass]

Can we see those see gull pictures? Im an all out bird nut and would love see some of your work. BTW all my wildelife shots thatwere takenin less than a month because my XTI broke. So my next body upgrade is probably going too be the 7D!

[Don Burkett]

I have put up a few more samples of the 7D if you're interested. Personally, I still like the camera. [View:http://www.pbase.com/dbrasco/canon_7d]